hAVE YOU CHECKED THE WHEEL FLANGE DEPTH. If its a Marklin loco it should be ok. If its not, then the flange depth could be smaller if it was originally a 2 rail loco. You have 3 choices if its the latter. 1/ don use it. 2/ run the loco at faster speeds over that switch. 3/ change the wheels on the loco.
The main thing is to thoroughly identify the problem. Personally have not had any problems with either of my double slip switches. The switch in you picture looks like it has been well used and without any problems so maybe it is the loco. Does it work with all your other Marklin locos?
Hope this helps. If not more information and pictures might help more.
Have fun.

Dereck

All Marklin Locos and rolling stock should have the same wheel flange depth. I am not anywhere near my Marklin so cant tell you right now.

Dereck

ps, the wheel flanges stop the wheels falling between the cracks so to speak. They keep the rolling stock moving at the same level or maybe slightly above. That's why Marklin have designed the wheels this way, to match their track. Other model railway makers have there own rail height etc so necessitate having wheel flanges to match their track.

Dereck

Ah! Yes!
Quoting master Yoda: Subtle problem this is!

There are a couple of things to look at.
It happens with the 3132, i.e short wheelbase, and one of the axles may present a poor contact with the track.
I think I remember one of the axles is pushed to the track with a small spring, simple "gravity" won't do here.

First , from your original picture, it looks like the base contact plate (that's supposed to catch the flanges ) could use a little cleaning (isopropyl alcohol or lighter fluid on a cotton swab) )

Second, JohnjeanB's photo reminded me of an annoying quirk of these early 5128 and 5207 equipped with the troublesome DP/DT contacts!!

The purpose of these contacts is to connect the adjacent small pieces of rail either to the "ground (i.e the rails) or the center contact (i.e the pukos) depending on the position of the switch!

Going "straight", they should be connected to ground, as to bridge the gap between rails going over the crossing

Going "turn" they should be connected to the pukos , to bridge the gap between pukos because otherwise locos with a short pick up shoe would loose contact: or create a short-circuit with the rails

These small unprotected contacts underneath have a tendency to corrode relatively rapidly .

In normal use, there's quite a lot of arcing and vibrations going on there each time a train passes!

The easy way (no removal from the layout, no need to open) to test is to verify with an ohmmeter that the little pieces of rail are switched correctly from ground/puko, corresponding on the switch straight/turn position

If fails, then you'll have to remove the Double slip from the layout and clean the contacts from underneath.

Good luck!

Cheers

Jacques

Hi Harlov
Looks great. Bravo.
Jean

The answer to this question was in my reply....

"..... Second, JohnjeanB's photo reminded me of an annoying quirk of these early 5128 and 5207 equipped with the troublesome DP/DT contacts!!

The purpose of these contacts is to connect the adjacent small pieces of rail either to the "ground (i.e the rails) or the center contact (i.e the pukos) depending on the position of the switch!

Going "straight", they should be connected to ground, as to bridge the gap between rails going over the crossing

Going "turn" they should be connected to the pukos , to bridge the gap between pukos because otherwise locos with a short pick up shoe would loose contact: or create a short-circuit with the rails ...."

I know it takes a little bit of investigation to figure it out, but actually these are fairly commeon in 2 rail layouts were you have to commute the polarity of rails in switches.

Hope this helps

Jacques